ox-texinfo: Offer to open produced file from dispatcher

* lisp/ox-texinfo.el (texinfo): Offer to open produced file from
  dispatcher.

File is opened through `org-open-file' since texinfo back-end can
output multiple formats.

lisp/ox-texinfo.el

@@ -86,7 +86,11 @@
   :menu-entry
   '(?i "Export to Texinfo"
        ((?t "As TEXI file" org-texinfo-export-to-texinfo)
-	(?i "As INFO file" org-texinfo-export-to-info)))
+	(?i "As INFO file" org-texinfo-export-to-info)
+	(?o "As INFO file and open"
+	    (lambda (a s v b)
+	      (if a (org-texinfo-export-to-info t s v b)
+		(org-open-file (org-texinfo-export-to-info nil s v b)))))))
   :options-alist
   '((:texinfo-filename "TEXINFO_FILENAME" nil nil t)
     (:texinfo-class "TEXINFO_CLASS" nil org-texinfo-default-class t)